The latest Greenhouse Gas Bulletin.pdf by the World Meteorological Organization reports data showing that the worldwide concentrations of greenhouse gases, carbon dioxide, methane, and nitrous oxide have continued to rise and "reached new highs in 2010" with reported averaged values of 389.0 ppb, 1,808 ppb, and 323.2 ppb, respectively.

The following illustration shows that although annual growth rate (ppm/year) varies widely (lower graph), the relative concentration of carbon dioxide has increased steadily (upper graph).  The report provides similar results for methane and nitrous oxide.  When coupled with the results of the International Energy Outlook 2011 (see Sustainability Law Talk post on Nov. 1, 2011) these data suggest a trend of increasing concentrations of greenhouse gases.